Intraspecific variation in integumental pore signatures in the genus Pleuromamma (Copepoda: Calanoida)

Intraspecific variation in the pore signature of calanoid copepods is evident between individuals within a single geographical area (within-sample variation) and between different geographical area (geographical variation). Previous studies, however, have tended to consider only geographical variation, neglecting within-sample variation; thus the question remains on how representative the data are of biogeographic divergence within a species. Eight species of the metridinid genus Pleuromamma are examined and the extent of intraspecific variation in pore signatures is assessed here in terms of within-sample variation. In general, the degree of intraspecific variation increases with increasing number of the total integumental pores and is limited to 10% or less of the total. Intraspecific variation reflects not only genetic variability within a species but also genetic similarities between the species within a genus. This paper also re-examines published data on intraspecific variation in pore signatures. Samples as small as five individuals will identify > 95% of potential sites of pores.